Lifestyle Factors During the Midlife and Subclinical Carotid Atherosclerosis Later in Life: The Study of Women's Health Across the Nation

Abstract

Menopause has adverse effects on cardiometabolic profiles that are linked to an accelerated progression of atherosclerosis and increased risk of cardiovascular disease in women. Thus, the menopausal transition may be a critical window for cardiovascular prevention in women, and lifestyle improvements during the menopausal transition may counteract the menopause-induced atherosclerotic risk. However, the potential impacts of lifestyle behaviors during the midlife on atherosclerosis later in life among women are still unclear. This dissertation evaluates the prospective associations of various lifestyle factors during the midlife with subclinical carotid atherosclerosis later in women’s life. Data from the Study of Women’s Health Across the Nation were used. Repeatedly collected lifestyle-related exposures, including dietary intake, smoking status, and physical activity, were available over 10 years. The measures of subclinical carotid atherosclerosis included common carotid artery intima-media thickness, adventitial diameter, and carotid plaque, all collected approximately 14 years after the baseline. In Chapter 2, the prospective associations between the intakes of eight beverage groups (coffee, tea, sugar-sweetened beverages, artificially sweetened beverages, fruit juices, whole milk, milk with lower fat content, and alcoholic beverages) during the midlife and subclinical carotid atherosclerosis were examined. A total of 931 midlife women were included in this analysis. The main findings indicated that occasional coffee intake during the midlife (no more than 2 cups per day) was positively associated with intima-media thickness later in life whereas moderate-to-heavy intake (more than 4 cups per day) might be inversely associated with intima-media thickness. Further, moderate intake of alcoholic beverages was inversely associated with intima-media thickness. In Chapter 3, the prospective associations of empirically derived dietary patterns with subclinical carotid atherosclerosis were assessed. A total of 1,246 midlife women were included in this analysis. Three statistical methods, including principal component analysis, reduced rank regression, and partial least squares regression, were used to identify dietary patterns. A Western dietary pattern was identified from each method. Further, a positive association between the Western diet and intima-media thickness was found under all three statistical methods. The findings suggested that the adoption of a diet low in red meat, processed meat, deep fried products, and sugar-sweetened beverages during the midlife might protect against future atherosclerosis in women. In Chapter 4, a 10-year average midlife Healthy Lifestyle Score was constructed using data on smoking, diet, and physical activity from 1,143 women. The prospective association between the Healthy Lifestyle Score and subclinical carotid atherosclerosis was evaluated. The prevalences of healthy behaviors were extremely low in midlife women. Further, women who had a healthy lifestyle during the midlife, composed of abstinence from smoking, having a healthy diet, and engagement in regular physical activity, had less subclinical carotid atherosclerosis later in their life. Among the three components of the Healthy Lifestyle Score, abstinence from smoking had the strongest association with subclinical carotid atherosclerosis. This dissertation highlights the midlife as a pivotal period for cardiovascular prevention in women and suggests that primary prevention efforts should focus on modifiable behaviors including diet, smoking, and physical activity. In the final chapter, the public health implications of the findings are discussed, and potential future research directions are reviewed.